| At present, main three technologies including pre-combustion separation, post-combustion separation and oxy combustion are the state of arts on CO2emission contol in powerplant. Among these technologies, chemical absorption process based on MEA absorbent is considered to be the most mature and promising. However, some shortcomings like high energy demand have been a stumbling block to its further industrialization. Recent Researches indicate a novel CO2separation technology based on hollow fiber membrane contactor (HFMC) has great potential to reduce the energy penalty. Compared with traditional chemical absorption process, there are few researches on absorbent selection and invention for the HFMC process. Therefore, in this thesis blended absorbent solutions will be developed and explored to develope novel absorbents for adapting to the HFMC process, and the membrane wetting issue will also discussed.For the experiments of CO2membrane vacuum regeneration (MVR),the results showed greater regeneration performance can be achieved with higher regeneration temperature, lower regeneration pressure and more sweeping stream. Among the MEA-based blended amine solutions,20%w.t. MEA+10%w.t. AMP had the best regeneration performance,and AMP could be considered as a good promoter for MEA-based blended absorbents in MVR process.In this research, the performance of the CO2membrane absortion and MVR process with different aqueous ammonia (AM) blends was investigated. It showed that potassium sarcosinate, AMP and TETA could improve CO2removal rate and membrane absorption rate. Compared with AMP and TETA, potassium sarcosinate was more environmentally friendly and suitable to be a promoter. With the condition of sweeping steam, AM+AMP had the highest absorption rate at lean loading and highest average absorption rate, while AM+TETA had the largest circle capacity. AM+potassium sarcosinate salt also had a good performance on all the aspects mentioned above. In conclusion, potassium sarcosinate, AMP and TETA could be considered as pretty good additives to improve the performance of blended solvents based AM in membrane separation and MVR process.The influences of sweeping stream and regeneration pressure on the energy consumption of different absorbents were studied. Results showed the energy consumption decreased with the increase of regeneration pressure and the decrease of sweeping stream. There is an optimal regeneration pressure which is20-30kPa. Due to higher regeneration mass transfer rate and regeneration extent at high regeneration pressure, DEA and AMP had potential of reducing MVR energy consumption more easily than MEA. Neglecting the cost of sweeping stream, the energy consumption of20%MEA+10%AMP is732.6KJe/kgCO2, less than any other blended amines at70％.Derived from the characteriazation anlysis of polypropylene (PP) membrane in the long-term experiment and immersing test, it indicated membrane wetting could be attributed to the intrusion of PP membrane fibers by absorbents. After intrusion, the mean pore diameter of membrane became larger, and roughness of the membrane surface also changed. High surface tension has positive influence on preventing membrane wetting, so less membrane wetting can be found as immersing in potassium sarcosinate solventdue to its high surface tension. Transmembrane pressure could be considered as a key factor to affect membrane wetting during long-term experiment, the membrane was more likely to be wettedas the transmembrane pressure increased. However, under fixed transmembrane pressure, membrane wetting become more difficult with the higher surface-tension liquid such as potassium sarcosinate. |
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